What is so ironic about "The Blue Hotel"?

The irony in Stephen Crane's story "The Blue Hotel" is in the fact that the Swede comes to Fort Romper expecting to be killed because he has formed a false picture of the Wild West from reading dime-novels filled with violence and written by hacks who know nothing about the real West. Although the Swede finds himself in a peaceful little hotel where the biggest excitement is a card game with no money involved, and no one is wearing a holstered six-shooter, he is suspicious of everyone and everything. The Easterner understands that the Swede's bizarre behavior is caused by his own imagination.

"Oh, I don't know, but it seems to me this man has been reading dime-novels, and he thinks he's right out in the middle of it--the shootin' and stabbin' and all."

"But," said the cowboy, deeply scandalized, "this ain't Wyoming, ner none of them places. This is Nebrasker."

By his own actions, the Swede brings about the very thing he was afraid of. He quarrels with a gambler in a saloon after vacating the Blue Hotel, and the gambler kills him with a knife.

Irony is usually like a joke that would be funny if it were not painful or sad or tragic. The Swede is a bit ridiculous and comical up until the point where the gambler reacts to the drunken Swede's abuse.

There was a great tumult, and then was seen a long blade in the hand of the gambler. It shot forward, and a human body, this citadel of virtue, wisdom, power, was pierced as easily as if it had been a melon. The Swede fell with a cry of supreme astonishment.